Motor Control Device Phase Error Integration for Precision Positioning
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Solution Overview
Problem
Conventional motor control methods face challenges in maintaining high precision positioning control, especially when the rotation speed of the motor changes, due to dead zones in feedback control caused by pulse signal deviations and loss of position information during start or stop operations.
Innovation Solution
A motor control device that includes a target cycle recording portion, a measured cycle recording portion, and a phase error calculating portion, which adjust power supplied to the motor based on integrated phase errors and error pulse counting to maintain precise control, even when the rotation speed changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If difference in count number between reference pulse signal and encoder pulse signal is used as deviation in feedback control, then control simplicity is improved, but measurement precision deteriorates due to dead zone below one pulse
Solution Approach 1:
The patent transitions from using count number difference (discrete, integer-based) to using difference in generation cycle (continuous, time-based) of pulse signals. This dimensional change allows for sub-pulse precision measurement by measuring time intervals between corresponding pulses rather than counting discrete pulse events, thereby eliminating the dead zone problem while maintaining control simplicity.
2Measurement precision
If difference in generation cycle between reference pulse signal and encoder pulse signal is used as deviation, then position measurement precision is improved, but information is lost when deviation exceeds generation cycle
Solution Approach 1:
The patent segments the deviation measurement into multiple cycles by recording generation cycle differences for several consecutive pulses (e.g., 3 cycles) and calculating average deviation. This segmentation approach allows the system to handle large deviations that exceed single pulse generation cycles by distributing the measurement across multiple cycles, preventing information loss while maintaining high precision.
Solution Approach 2:
The patent performs preliminary recording of generation cycle data for multiple pulses before calculating the final deviation. By pre-recording the generation cycles of reference pulses and encoder pulses in buffers, the system prepares the necessary data in advance, allowing accurate deviation calculation even when the motor starts or stops and large deviations occur.
3Speed
If conventional feedback control is used during motor start or stop, then control response is improved, but position control fails when deviation exceeds pulse signal generation cycle
Solution Approach 1:
The patent performs preliminary recording of generation cycle data for multiple consecutive pulses in buffers before deviation calculation. This preliminary action ensures that sufficient data is available even during dynamic conditions like motor start or stop, allowing the control system to maintain reliable position control by calculating deviation from accumulated data rather than relying on single-pulse measurements.
Data Source
AI summary
A target cycle recording portion (821) records target cycle data (Tref) into a first ring buffer (824) each time a reference pulse signal (Ps) is generated, thereby recording the target cycle data (Tref) sequentially into the first ring buffer (824). A measured cycle recording portion (822) records measured cycle data (Tenc) into a second ring buffer (825) each time an encoder pulse signal (Pe) is generated, thereby recording the measured cycle data (Tenc) sequentially into the second ring buffer (825). A phase error calculating portion (823) calculates a phase error PHE by integrating a difference between the target cycle data (Tref) and the measured cycle data (Tenc) that are sequentially recorded in data buffers respectively in correspondence with each other in the two ring buffers.